Chapter 5 Client Design

227

5.3.5 Processing Return Values

J2EE applications generally use Web components to generate returned data for dis 

play. For example, a client accessing an order tracking service might display track 

ing information in a Web page using an HTML browser. The J2EE component may

take the values returned from the Web service and handle them just like any other

Java object. For example, a Web component in a J2EE client application might

query the status of an order from an order tracking service, which returns these

values within a JavaBeans like object. The client component places the returned

object in the request scope and uses a JSP to display its contents. (See Code

Example 5.9.)

Order ID: ${bean.orderId}

Status: ${bean.status} 

Name: ${bean.givenName} ${bean.familyName} 

Code Example 5.9

JSP for Generating an HTML Document

The J2EE platform has a rich set of component technologies for generating

Web content, including JavaServer Pages (JSP) technology for generating HTML

content and Java Standard Tag Libraries (JSTL). JSTL is a set of tags that assist a

client developer in formatting JSPs. For example, JSTL provides additional tags

for looping, database access, object access, and XSLT stylesheet transformations.

The current version of JSP (2.0), along with future versions, provides an expres 

sion language that allows a developer to access bean properties. Together, devel 

opers can use JSTL and JSP technologies to generate HTML documents from data

retrieved from a service. For example, a developer might generate the following

HTML document for the order details (see Code Example 5.10). This HTML doc 

ument is returned to the HTML browser client that requested the service. 

Order: 54321

Status: SHIPPED